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HB 13—2007
areas
Handbook
Electrical equipment for hazardous
HB 13—2007

2. This Australian Handbook was prepared by Committee P-012, Hazardous Areas Competency
Standards Advisory Panel. It was approved on behalf of the Council of Standards Australia on
14 December 2007.
This Handbook was published on 31 December 2007.
The following are represented on Committee P-012:
• Australian Chamber of Commerce and Industry
• Australian Coal Association
• Australian Electrical and Electronic Manufacturers Association
• Australian Industry Group
• Australian Institute of Petroleum
• Australian Petroleum Production and Exploration Association
• Certification Interests (Australia)
• Department of Infrastructure, Energy and Resources, Tas.
• ElectroComms and Energy Utilities Industries Skills Council
• Electrotechnology Industry Training Organisation
• Energy Networks Association
•
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Engineers Australia
• Institute of Electrical Inspectors
• Institute of Instrumentation, Control and Automation Australia
• Mining Electrical and Mining Mechanical Engineering Society
• NSW Department of Primary Industries, Mineral Resources
• New South Wales Grain Corporation
• New Zealand Hazardous Areas Electrical Coordinating Committee
• Simtars (Natural Resources, Mines and Water)
• TAFE NSW
• The Royal Australian Chemical Institute
• WorkCover New South Wales
Standards Australia wishes to acknowledge the participation of the expert individuals that
contributed to the development of this Standard through their representation on the
Committee.
Keeping Standards up-to-date
Australian Standards® are living documents that reflect progress in science, technology and
systems. To maintain their currency, all Standards are periodically reviewed, and new editions
are published. Between editions, amendments may be issued.
Standards may also be withdrawn. It is important that readers assure themselves they are
using a current Standard, which should include any amendments that may have been
published since the Standard was published.
Detailed information about Australian Standards, drafts, amendments and new projects can
be found by visiting www.standards.org.au
Standards Australia welcomes suggestions for improvements, and encourages readers to
notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at
mail@standards.org.au, or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

3. HB 13—2007
Handbook
Electrical equipment for hazardous
This is a free 10 page sample. Access the full version online.
areas
Originated as HB 13—1988.
Previous edition 2000.
Fourth edition 2007.
COPYRIGHT
© Standards Australia
All rights are reserved. No part of this work may be reproduced or copied in any form or by
any means, electronic or mechanical, including photocopying, without the written
permission of the publisher.
Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia
ISBN 0 7337 8514 X

4. HB 13—2007 2
PREFACE
In the last decade there has been an increased awareness of the use of electrical equipment
in potentially explosive gas and dust atmospheres. This has led to a substantial expansion of
recognized explosion-protection techniques, construction and test specifications, codes of
practice and safety legislation.
The range of equipment is extensive, offering designs and types to suit specific situations.
An incorrect selection or installation of equipment may prove to be not only a costly error,
but also unsafe.
Many people have an interest in the safe use of electrical equipment in hazardous areas—
plant management, consulting engineers, manufacturers, electrical contractors, construction
and maintenance personnel, electrical inspectors, workshops and insurance underwriters.
The main objective of this Handbook is to provide a basis for understanding the principles
involved in the identification of a hazardous area, relevant statutory requirements and the
selection and installation, maintenance, testing, overhaul and repair of appropriate electrical
equipment.
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This Handbook also provides a basic introduction to the relevant Australian, New Zealand,
Joint (Australian/New Zealand) and International Standards dealing with hazardous areas.
During the 1990s two fundamental changes have occurred in the explosion-protected
electrical equipment field, in Australia and New Zealand.
The first took place in the early 1990s, when an Active Cooperation Agreement between
Standards Australia and Standards New Zealand was signed for the preparation and
marketing of Joint Standards (Australian/New Zealand).
This Agreement came into effect on 1 July 1992 and since then several Joint Standards have
been published within the Hazardous Areas field.
While not all Australian Standards applicable to hazardous areas have progressed to Joint
Standards status, almost all the Australian Standards that are not joint, are applicable in
New Zealand either through citation in regulations, principally by NZECP 24, or through
citation in Joint Standards.
There are a small number of ‘New Zealand only’ Standards applicable to some aspects of
hazardous areas, however they are generally not consistent with the homologous joint series
and therefore should be considered as obsolescent Standards, which are retained for
particular special applications.
As a consequence of this, the term ‘Joint Standard’ should be read in this document to
include all Standards referenced, whether or not they are official Joint Standards. Where a
particular Standard does not have applicability in New Zealand that aspect will be
highlighted in the text.
In respect to Standards relating to competencies, there will be slight differences for New
Zealand due to the differing competency and qualification frameworks; however these
differences do not apply to the ‘technical’ aspects of the requirements and therefore the
AS/NZS 4761 Series (EEHA Competency Standards) is fully applicable in New Zealand.
The second major change was the strategic decision made by the Joint Committee EL-014
in December 1996, to adopt all the relevant IEC Standards and publish them as Joint
Standards (AS/NZS).

5. 3 HB 13—2007
The rationale behind the adoption of the IEC Standards is: Australia and New Zealand are
part of the global economy and must compete on such a basis and to allow freedom of trade.
The IECEx Scheme permits apparatus certified in Member Countries of the Scheme to be
used in Australia and New Zealand without further certification being required by an
Australian or New Zealand testing laboratory (Section 7 for further details).
At the same time the European countries, who now operate under the ATEX Directives and
EN (CENELEC) Standards, are moving to adopt the IEC Standards.
Leading up to the adoption of the IEC Standards as Joint Standards, both countries had
considerable input into their formulation and it became clear that in the interests of
rationalization there was no impediment from a technical or philosophical point of view in
adopting the IEC Standards in their entirety.
Due to the ongoing alignment with IEC Standards the term ‘equipment’ is being replaced by
the term ‘apparatus’, in the most recent published Joint Standards (AS/NZS). In this
Handbook you may find in some sections references to one or another of these terms, but
they should be considered equivalent.
Regarding the numbering of Standards in Australia and New Zealand, different patterns co-
exist nowadays, and some examples are:
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AS 2380.1 (valid in Australia and New Zealand)
NZ 5425 (valid only in New Zealand)
AS/NZS 3800 Joint Standard—Australia/New Zealand
AS/NZS 60079.0 Joint Standard—Australia/New Zealand—adoption of IEC 60079-0
As the long term future of this Handbook is still being discussed by the relevant
Committees—P-012, EL-014 and EL-023—and considering that most of the references are
out of date, Committee P-012 decided to embark on a light revision just for updating the
references.
Therefore the changes introduced in this edition are basically those relating to the update of
all the references included in this publication.
Committee P-012—Hazardous Areas Competency Standards Advisory Panel has overseen
the preparation of this Edition.
The cooperation and assistance of CSE-Ex, Cooper Electrical Australia, Orica Engineering
Ltd, Standards Australia and TAFE—NSW (Manufacturing and Engineering Education
Services) in the preparation of photos, diagrams and figures (already used in the previous
Edition) are recognized and highly appreciated.
WARNING
THE INFORMATION IN THIS HANDBOOK IS INTENDED ONLY AS A
GUIDE TO PROVIDE INFORMATION ON THE BACKGROUND AND
PRINCIPLES IN THIS EXTREMELY COMPLEX FIELD OF
ELECTROTECHNOLOGY. THIS INFORMATION DOES NOT PURPORT TO
COVER ALL THE ISSUES THAT MAY ARISE IN THE DESIGN, SELECTION,
INSTALLATION, TESTING, MAINTENANCE, REPAIR, OVERHAUL OR
MODIFICATION OF EXPLOSION-PROTECTED ELECTRICAL EQUIPMENT.
UNDER NO CIRCUMSTANCES CAN THE INFORMATION CONTAINED IN
THIS HANDBOOK BE USED AS AN ALTERNATIVE TO THE RELEVANT
STANDARDS OR THE EQUIPMENT CERTIFICATION/APPROVAL
DOCUMENTATION.

6. HB 13—2007 4
CONTENTS
Page
SECTION 1 WHAT IS A HAZARDOUS AREA?
1.1 INTRODUCTION ....................................................................................................... 8
1.2 HAZARDOUS AREAS ............................................................................................... 8
1.3 CONDITIONS FOR AN EXPLOSION ....................................................................... 9
1.4 FLAMMABLE MATERIALS ..................................................................................... 9
1.5 PROPERTIES OF FLAMMABLE MATERIALS ..................................................... 10
1.6 IGNITION SOURCES............................................................................................... 18
1.7 TOXICITY ................................................................................................................ 23
SECTION 2 WHO IS RESPONSIBLE?
2.1 INTRODUCTION ..................................................................................................... 24
2.2 UNDERGROUND COAL MINING.......................................................................... 24
2.3 OTHER INDUSTRIES .............................................................................................. 25
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2.4 COMPETENCIES OF PERSONNEL........................................................................ 29
SECTION 3 THE IMPORTANCE OF STANDARDS
3.1 INTRODUCTION ..................................................................................................... 30
3.2 AUSTRALIAN, NEW ZEALAND AND JOINT STANDARDS (AS/NZS) ............. 30
3.3 INTERNATIONAL STANDARDS........................................................................... 33
3.4 OTHER NATIONAL STANDARDS ........................................................................ 34
SECTION 4 CLASSIFICATION OF HAZARDOUS AREAS
4.1 INTRODUCTION ..................................................................................................... 36
4.2 RESPONSIBILITY ................................................................................................... 36
4.3 RELEVANT INFORMATION .................................................................................. 37
4.4 TYPE OF HAZARD.................................................................................................. 37
4.5 ZONES 0, 1 AND 2 (GASES) ................................................................................... 37
4.6 ZONES 20, 21 AND 22 (DUSTS) ............................................................................. 42
4.7 IMPLEMENTATION OF MANAGEMENT PRACTICES FOR GAS/VAPOUR
AND DUST AREAS ................................................................................................. 46
4.8 SUMMARY OF AREA CLASSIFICATION............................................................. 48
SECTION 5 EXPLOSION-PROTECTION TECHNIQUES
5.1 INTRODUCTION ..................................................................................................... 49
5.2 EXPLOSION-PROTECTION TECHNIQUES .......................................................... 49
5.3 Ex d - FLAMEPROOF ENCLOSURE....................................................................... 51
5.4 Ex e - INCREASED SAFETY .................................................................................. 57
5.5 Ex i - INTRINSIC SAFETY ...................................................................................... 60
5.6 Ex m - ENCAPSULATION....................................................................................... 68
5.7 Ex n - NON-SPARKING ........................................................................................... 68
5.8 Ex o - OIL-IMMERSION .......................................................................................... 70
5.9 Ex p - PRESSURIZED ROOMS OR PRESSURIZED ENCLOSURES..................... 70
5.10 Ex q -POWDER-FILLING ........................................................................................ 73
5.11 Ex s - SPECIAL PROTECTION................................................................................ 73
5.12 Ex v - VENTILATION .............................................................................................. 74
5.13 Ex h - HERMETIC SEALING................................................................................... 75
5.14 Ext ‘tD PROTECTION BY ENCOSURE Ex ‘tD’ (DIP) - DUST IGNITION
PROTECTION .......................................................................................................... 75
5.15 MIXED TECHNIQUES ............................................................................................ 79

7. 5 HB 13—2007
SECTION 6 GENERAL REQUIREMENTS FOR EXPLOSION-PROTECTION
TECHNIQUES
AND REQUIREMENTS OF OTHER RELEVANT STANDARDS
6.1 INTRODUCTION ..................................................................................................... 81
6.2 AS 2380.1 AND AS/NZS 60079.0—GENERAL REQUIREMENTS........................ 81
6.3 DEGREES OF PROTECTION (IP CODE) ............................................................... 85
6.4 CABLE GLANDS ..................................................................................................... 88
6.5 ELECTRICALLY HEATED OVENS ....................................................................... 89
6.6 BATTERY OPERATED VEHICLES........................................................................ 89
6.7 ELECTRICAL SYSTEMS OF DISPENSING APPARATUS ................................... 90
6.8 ELECTROSTATIC PAINT AND POWDER SPRAY GUNS ................................... 90
6.9 GAS DETECTION INSTRUMENTS ....................................................................... 90
6.10 UNDERGROUND COAL MINING.......................................................................... 91
SECTION 7 CERTIFICATION AND APPROVAL OF APPARATUS
7.1 INTRODUCTION ..................................................................................................... 92
7.2 CERTIFICATION/APPROVAL OF Ex EQUIPMENT IN AUSTRALIA AND
NEW ZEALAND ...................................................................................................... 93
7.3 THE IECEx SCHEME............................................................................................... 97
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7.4 OVERSEAS TESTING AND CERTIFICATION, OUTSIDE THE IECEx
SCHEME................................................................................................................. 101
7.5 APPROVED MINING EQUIPMENT ..................................................................... 102
7.6 EXEMPTION FROM CERTIFICATION................................................................ 105
7.7 PERSONAL EQUIPMENT ..................................................................................... 105
SECTION 8 SELECTION OF APPARATUS
8.1 GENERAL .............................................................................................................. 106
8.2 APPARATUS FOR GASES ................................................................................... 107
8.3 APPARATUS FOR DUSTS .................................................................................... 113
8.4 APPARATUS ABOVE A HAZARDOUS AREA ................................................... 114
8.5 APPARATUS NOT PERMITTED .......................................................................... 115
8.6 SELECTION OF REPAIRED OR EXISTING EQUIPMENT................................. 115
SECTION 9 INSTALLATION OF EXPLOSION-PROTECTION APPARATUS AND
SYSTEMS
9.1 INTRODUCTION .................................................................................................. 117
9.2 GENERAL INSTALLATION REQUIREMENTS .................................................. 117
9.3 PROTECTION AND ISOLATION OF ELECTRICAL INSTALLATIONS ........... 118
9.4 COMPONENTS OF AN INSTALLATION............................................................. 119
9.5 WIRING SYSTEMS................................................................................................ 120
9.6 INSTALLATIONS IN ZONE 0 AREAS ................................................................. 122
9.7 INSTALLATIONS IN ZONE 1 AND ZONE 2 AREAS ......................................... 123
9.8 INTRINSICALLY SAFE ELECTRICAL APPARATUS AND SYSTEMS ........... 123
9.9 FLAMEPROOF ELECTRICAL APPARATUS....................................................... 125
9.10 INCREASED SAFETY ELECTRICAL APPARATUS........................................... 127
9.11 INSTALLATIONS IN ZONE 20, 21 AND 22 AREAS ........................................... 129
9.12 SPECIFIC OCCUPANCIES .................................................................................... 130
9.13 VERIFICATION DOSSIER .................................................................................... 131
9.14 PRE-COMMISSIONING INSPECTION AND TESTING ...................................... 132
SECTION 10 MAINTENANCE AND INSPECTIONS
10.1 INTRODUCTION ................................................................................................... 134
10.2 USE OF GAS DETECTORS ................................................................................... 134
10.3 QUALIFICATIONS OF PERSONS CARRYING OUT INSPECTIONS AND
MAINTENANCE .................................................................................................... 134

8. HB 13—2007 6
10.4 RELEVANT STANDARDS.................................................................................... 134
10.5 STATUTORY REGULATIONS ............................................................................. 135
10.6 CURRENT STANDARDS ...................................................................................... 135
10.7 IMPORTANT MAINTENANCE ASPECTS........................................................... 135
10.8 RECOMMENDATIONS ......................................................................................... 145
SECTION 11 TESTING AND FAULT FINDING
11.1 GENERAL .............................................................................................................. 148
11.2 TESTING INTRINSICALLY SAFE SYSTEMS ..................................................... 148
11.3 TESTING OF EXPLOSION-PROTECTED ELECTRICAL APPARATUS
OTHER THAN INTRINSICALLY SAFE APPARATUS ....................................... 149
11.4 TESTS IN THE SAFE AREA ................................................................................. 149
11.5 PORTABLE APPARATUS..................................................................................... 149
11.6 FAULT FINDING ................................................................................................... 150
11.7 TYPICAL USES AND RESTRICTIONS OF USE OF TEST APPARATUS.......... 150
SECTION 12 OVERHAUL AND REPAIR
12.1 GENERAL .............................................................................................................. 159
12.2 OVERHAULS ......................................................................................................... 159
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12.3 TRACEABILITY/MARKING................................................................................. 160
12.4 MINIMUM MARKING........................................................................................... 160
12.5 SUBSEQUENT OVERHAULS............................................................................... 160
12.6 OVERHAUL CERTIFICATE ................................................................................. 160
12.7 SCOPE OF WORK.................................................................................................. 160
12.8 REPAIR OR REPLACE .......................................................................................... 161
12.9 REPAIR WORK NOT AFFECTING THE EXPLOSION-PROTECTION
INTEGRITY............................................................................................................ 162
SECTION 13 CERTIFIED /ACCREDITED WORKSHOPS
13.1 GENERAL .............................................................................................................. 163
13.2 THE CERTIFIED/ACCREDITED WORKSHOP.................................................... 163
13.3 TYPES OF WORKSHOPS...................................................................................... 163
13.4 PERSONNEL .......................................................................................................... 163
13.5 FACILITIES............................................................................................................ 163
13.6 EXAMPLE OF A VERIFICATION SCHEME PROGRAM FOR WORKSHOP
CAPABILITIES ...................................................................................................... 164
13.7 THE RESPONSIBILITIES OF COMPETENT PERSONS...................................... 165
13.8 RECORDS............................................................................................................... 166
13.9 MARKING .............................................................................................................. 166
13.10 CONDITIONS FOR APPARATUS RELEASE....................................................... 166
13.11 IECEx CERTIFIED SERVICE FACILITIES PROGRAM ...................................... 166
SECTION 14 GAS DETECTORS
14.1 INTRODUCTION ................................................................................................... 167
14.2 WHAT IS THE MAKE-UP OF THE ATMOSPHERE AROUND US?................... 168
14.3 SOME COMMON PROPERTIES OF GASES AND VAPOURS ........................... 169
14.4 THE DIFFERENCES BETWEEN GASES AND VAPOURS ................................. 170
14.5 APPLICABLE STANDARDS FOR EXPLOSION-PROTECTION AND OTHER
REQUIREMENTS OF GAS AND VAPOUR DETECTORS .................................. 171
14.6 APPARATUS MARKING ...................................................................................... 172
14.7 GAS AND VAPOUR DETECTORS TESTED IN AUSTRALIA PRIOR TO 2000 173
14.8 FUNDAMENTAL PRINCIPLES IN THE USE OF COMBUSTIBLE GAS AND
VAPOUR INSTRUMENTS ................................................................................... 173
14.9 THE INSTRUMENT INSTRUCTION MANUAL .................................................. 175

9. 7 HB 13—2007
14.10 SUMMARY OF VARIATIONS TO VAPOUR HAZARDS, DUE TO
TEMPERATURE CHANGES AND OTHER FACTORS. ...................................... 176
14.11 SOME COMMON TERMS USED WITH TOXIC GASES AND VAPOURS ........ 177
14.12 SAFETY WHEN USING A GAS DETECTOR IN A HAZARDOUS AREA ......... 179
14.13 OXYGEN DEFICIENCY ........................................................................................ 180
14.14 SPECIAL PRECAUTIONS WHEN USING A HIRED, BORROWED, OR
OTHERWISE UNFAMILIAR GAS OR VAPOUR DETECTOR............................ 182
14.15 THE ‘READ AND RUN’ CONCEPT FOR INEXPERIENCED OPERATORS ...... 182
14.16 THE CATALYTIC COMBUSTION DETECTION TECHNIQUE.......................... 183
14.17 CONTAMINATION OF GAS DETECTION SYSTEMS BY LIQUIDS ................. 184
14.18 SOME CONSIDERATIONS ABOUT FLASHPOINT AND TEMPERATURE...... 185
14.19 SOME INSTALLATION ‘DOs’ AND ‘DO NOTs’ OF PERMANENT GAS
DETECTION .......................................................................................................... 186
14.20 SUMMARY ............................................................................................................ 188
APPENDICES
A RELEVANT GOVERNMENT AND INDUSTRY BODIES ................................... 189
B AUSTRALIAN, NEW ZEALAND AND JOINT STANDARDS (AS/NZS) ........... 198
C RELEVANT OVERSEAS STANDARDS............................................................... 203
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D TESTING STATIONS, CERTIFYING AUTHORITIES AND STANDARDS
BODIES .................................................................................................................. 207

10. HB 13—2007 8
STANDARDS AUSTRALIA
Australian Standard
Electrical equipment for hazardous areas
SECT ION 1 WHAT IS A HA ZARDO US AREA?
1.1 INTRODUCTION
There is a danger of an explosion or fire occurring wherever flammable or combustible
materials are handled. This is graphically illustrated by the dreadful toll taken by coal
mining explosions in the past. For example in England in the last century hundreds of lives
were lost every year.
The hazard today exists not only in the coal mining industry but also in many other
industries. Major industries include the petrochemical, pharmaceutical, chemical, sewage
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treatment, and grain handling industries. In 1866, in a series of explosions in the Oaks
Colliery, 361 people were killed in one accident alone. In 1988 the Piper Alpha oil and gas
platform in the North Sea caught fire and exploded killing 167 workers. Smaller industries
involve such areas as paint shops and dry-cleaning premises. In many cases the hazards
occur in areas frequented by the public, for example petrol service stations.
In all these situations, electricity is used.
Where it is necessary to use electrical apparatus in an environment in which there may be
an explosion it is essential that measures are taken to eliminate the likelihood of an
explosive atmosphere occurring around any source of ignition or limiting the possibility of
an ignition source, (e.g. arcs, sparks or hot surfaces) occurring.
To prevent any of the electrical apparatus becoming a source of ignition for an explosion,
special precautions have to be taken in the design, construction, selection, installation and
maintenance of such apparatus.
Many incidents around the world have driven governments into establishing regulating
bodies and appropriate Standards and codes of practice. The codes of practice and
appropriate Standards must be adhered to, for it is not the many tasks performed correctly
but the one task performed incorrectly that could cause death, injury and plant destruction.
1.2 HAZARDOUS AREAS
A hazardous area is defined as an area in which an explosive atmosphere is present, or may
be expected to be present, in quantities such as to require special precautions for the
construction, installation, and use of potential ignition sources.
The explosive atmosphere may be caused by the presence of a flammable liquid, gas or
vapour or by the presence of combustible dust in suspension or in layers or a combination
of explosive gas and dust atmospheres.
In the design of industrial plants, every effort is usually made to minimize the extent of
hazardous areas but it may be difficult to ensure that an explosive atmosphere will never
occur.
Incorrect design of the plant may result in the occurrence of small, local fireballs which
could ignite other flammable materials and lead to extensive damage to the whole plant,
adverse effects to the environment and serious injuries to personnel.
© Standards Australia www.standards.org.au

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